The gradual rise in temperatures will generate a decrease in water flow that could endanger at the end of the century the survival of the Cola de Caballo waterfall in Ordesa National Park, in the Aragonese Pyrenees, in times of low water, according to a study carried out by researchers from the Geological and Mining Institute of Spain (IGME).

The research is based on the forecasts of climate models that foresee that the average temperature in the Pyrenees may rise at the end of the century between 2 and 7.1 degrees, ascent that will gradually cause less precipitation in the form of snow and the snow cover that forms will last less.

According to the study, in which members of the Otxola caving group have collaborated, the water discharged from the Garcés spring comes mainly from the infiltration of the snow melt, which also conditions the internal geometry of the karst duct network (geological formations shaped by water).

A quarter of this water infiltrates in a concentrated way through deep chasms that connect the land surface with this network galleries, discharging through the Garcés spring in just ten days.

However, the remaining three-quarters of the snow melt water infiltrates, diffusely, through the extensive network of fractures and joints that have the Paleocene-Eocene limestones that emerge on the surface of the land until reach the water table of the aquifer.

From that point, the groundwater begins to flow sub-horizontally with a laminar flow regime, reaching the discharge point at the Garcés spring after an underground trip lasting just over a year, according to the IGME in a press release.

Abundance of accumulated snow in fall, winter and spring guarantees a generous recharge of the aquifer through the efficient infiltration of the snow melt, which translates into a continuous and stable discharge of the aquifer, responsible for generating the base flow that maintains the visual splendor of the Cola de Caballo waterfall, which readers of the British newspaper ‘The Guardian’ have named as the most beautiful waterfall in the world.

If the forecasts of the climate models are confirmed, rainfall in the form of snow would reduce, which would cause the snow cover that is formed to last less and therefore the diffuse recharge that guarantees the discharge flows and the survival of the waterfall as it is known today would be reduced.

He IGME team of scientists It is made up of Jorge Jódar, Antonio González, Sergio Martos, Javier Heredia and Luis Javier Lambán (project manager) and has had the collaboration of Fernando Carmena, José Ignacio Gómez, Marta Quintana and Elena Villagrasa (director of the Park) as well as the Otxola caving group.

This activity is part of the European project PIRAGUA (EFA 210/16) “Assessment and prospective of the water resources of the Pyrenees in a context of climate change, and adaptation measures with impact on the territory (2018-2020)”.